1. Field of the Invention
The present invention relates to a plasma display which can reduce reflection of external light and a method of forming a black matrix in the plasma display.
2. Description of the Related Art
A typical plasma display forms an image by exciting fluorescent material using ultraviolet rays generated when gas disposed between a pair of substrates is discharged. The plasma display is divided into an AC type, a DC type, and a hybrid type.
FIG. 1 shows an example of a conventional AC type plasma display. Referring to the drawing, a plasma display includes a rear substrate 10, a first electrode 11 being an address electrode formed in strips on the rear substrate 10, a is dielectric layer 12 formed on the rear substrate 10 to cover the first electrode 11, a plurality of partitions 13 formed in strips on the upper surface of the dielectric layer 12 and defining a discharge space to prevent optical cross talk between discharge cells, and a fluorescent layer 15 coated on the inner surface of the discharge space.
A front substrate 18 is coupled above the partitions 13. A second electrode 16 and a third electrode 17 are formed on the lower surface of the front substrate 18 to cross the first electrode 11. The second and third electrodes 16 and 17 are formed of indium tin oxide (ITO) which is transparent. Here, a bus electrode 16a and 17a can be provided to reduce line resistance. The bus electrode 16a and 17a is limited in its width as narrow as possible to minimize blocking light which is generated by exciting the fluorescent material in the discharge space and passes through the front substrate 18. For example, the bus electrode 16a and 17a can be formed in a print method using metal such as silver (Ag) paste or a photolithography using a photosensitive film.
A dielectric layer 19 is formed on the lower surface of the front substrate 18 covering the second and third electrodes 16 and 17. A protective layer 21 can be coated on the lower surface of the dielectric layer 19. Also, a black matrix 22 is formed between the respective discharge cells.
In the operation of the plasma display having the above structure, the black matrix 22 does not reflect but absorbs part of external light (indicated by a dotted line in FIG. 2) input to the front substrate 18 so that contrast is improved.
As the width of the black matrix 22 increases, the reflectance of external light is lowered so that contrast is improved. However, the effect of the reduction of reflectance of external light due to an increase in the width of the black matrix 22 is not noticeable. Furthermore, when the width of the black matrix 22 is too great, light image emitted from the discharge space to the outside is blocked, thus lowering brightness.
Also, by blacking the color of the bus electrode 16a and 17a, provided to the second and third electrodes 16 and 17, the same effect as that of the black matrix 22 can be obtained. However, since the width of the bus electrode 16a and 17a is extremely narrow, there is a limit to lower the reflectance of external light.
To solve the above problems, it is an objective of the present invention to provide a plasma display adopting a black matrix in a groove formed in a front glass substrate to reduce reflection of external light so that contrast of an image can be improved, and a method of forming a black matrix in the plasma display.
Accordingly, to achieve the above objective, there is provided a plasma display comprising a rear substrate, a plurality of first electrodes formed in strips and parallel to each other on an inner surface of the rear substrate, a dielectric layer coated on the rear substrate to cover the first electrode, a plurality of partitions formed in strips on the dielectric layer, defining a discharge space, a fluorescent layer coated on an inner surface of the discharge space, a front substrate which is transparent and coupled above the partitions, second and third electrodes formed in strips and to be parallel to one another on an inner surface of the front substrate and to cross the first electrode, and a black matrix formed between a discharge cell constituted by a pair of the second and third electrodes and another discharge cell adjacent thereto, by filling a groove which is formed at the inner surface of the front substrate to be parallel to the second and third electrodes with a light shielding material.
It is preferred in the present invention that the black matrix is formed in a groove which is formed in the front substrate.
Also, it is preferred in the present invention that the profile of the black matrix has a dam shape.
Also, it is preferred in the present invention that the profile of the black matrix has a curved V-shape.
Also, it is preferred in the present invention that the height H of the black matrix, the incident angle xcex8 of external light and the distance D between adjacent black matrices have the relationship, H tan xcex8xe2x89xa7(D/2).
Also, it is preferred in the present invention that the height H of the black matrix is 30 through 60 micrometers.
Also, it is preferred in the present invention that the height H of the black matrix is 50 micrometers.
According to another aspect of the present invention, there is provided a method of forming a black matrix of a plasma display which comprises the steps of forming a groove of a predetermined pattern at an inner surface of a front glass substrate of the plasma display, filling the groove of a predetermined pattern with a light shield material, and fusing the black matric material to adhere to the glass substrate by burning the front glass substrate.
It is preferred in the present invention that the method further comprises a step of forming a protection film for preventing black matrix from spreading on an inner surface of the front glass substrate, after the step of burning.
Also, it is preferred in the present invention that the groove of a predetermined pattern on the inner surface of the front glass substrate is formed by pressing the front glass substrate by a mold.
Also, it is preferred in the present invention that the groove of a predetermined pattern on the inner surface of the front glass substrate is formed by etching the front glass substrate in a state in which a predetermined photoresist pattern is formed on the front glass substrate.
Also, it is preferred in the present invention that light shielding material is black inorganic pigment or material for a neutral density (ND) filter.
According to yet another aspect of the present invention, there is provided a method of forming a black matrix of a plasma display which comprises the steps of coating transparent paste which is a mixture of glass powder and adhesive and opaque paste which is a mixture of glass powder, adhesive and light shielding material on a film support body in a predetermined pattern, forming a green tape by pressing transparent paste on the film support body and the opaque paste, attaching the green tape on a front glass substrate of the plasma display to the green tape and removing the film support body, and performing a burning process so that the transparent paste and the opaque paste can be fused and adhered to the front glass substrate.
It is preferred in the present invention that the method further comprises a step of forming a protection film on an inner surface of the transparent paste and the opaque paste after the burning process.
According to further another aspect of the present invention, there is provided a method of forming a black matrix of a plasma display which comprises the steps of forming a green tape by coating a transparent paste which is formed by mixing glass powder and paste on a film support body, laminating the green tape on an inner surface of a front glass substrate of the plasma display, forming a groove of a predetermined pattern on the green tape, filling the groove with light shielding material, and fusing the black matrix material to adhere to the glass substrate by burning the front glass substrate.
It is preferred in the present invention that the step of forming a groove a predetermined pattern at the green tape is made by pressing the surface of the green tape using a mold.
Also, it is preferred in the present invention that the groove of a predetermined pattern on the green tape is formed by etching the surface of the green tape in a state in which a predetermined photoresist pattern is formed.
Also, it is preferred in the present invention that the method further comprises a protection film on the surface of the green tape.